Tag: biodiversity and its classifications

• Vertebrates are animals that have a backbone or spinal column, also called vertebrae.
• The five most well-known classes of vertebrates are mammals, birds, fish, reptiles, amphibians. They belong to the phylum Chordata.
  

The vertebral column, also known as the backbone or spine, is a bony skeletal structure found in vertebrates. It is formed from individual bones called vertebrae, which houses the spinal canal, a cavity that encloses and protects the spinal cord. Therefore, (d) is the correct answer. 

All chordates are characterised by three primary chordate features the presence of a notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits. The notochord, later on, gives rise to a bony vertebral column, which surrounds and protects the spinal cord. So, the correct answer is option B.

All vertebrates have a living endoskeleton. The characteristic of vertebrates without exception is the presence of a brain. The brain is set inside a bony box called as the cranium. Cranium is made up of eight bones. It protects the human brain from mechanical injury.
Therefore, the correct answer is option B.

Ostracoderms are considered the most primitive vertebrates, being jawless armored fish from the Paleozoic era. Other options like Cephalochordates are chordates but not vertebrates, while Placoderms and Cyclostomes appeared later or represent different lineages.

Herdmania is a tunicate (sea squirt). The foot is the structure that helps it anchor or remain embedded in the sandy substrate.

• The heart of vertebrates is ventrally placed.
• The body of vertebrates consists of serially arranged vertebrae which comprises of a major part of their axial exoskeleton, the vertebral column or the backbone.
• The coelom of vertebrates is large and well developed and it is of enterocoelous type.